CSIM 1.76: CNS Disease 1: Raised Intracranial Pressure, Stroke and Brain Oedema

Question 1

In those with raised intracranial pressure, what is the pressure in mmHg?

What movement does this cause?

Answer 1

Up to 10mmHg

Brain pulsates; expands and contracts with each heartbeat

Question 2

What are the potential causes of raised intracranial pressure?

Answer 2

Space-occupying lesions:
• Neoplasms (primary and metastatic)
• Abscesses
• Haemorrhages

Hydrocephalus

Question 3

Recall if the following are arterial or venous:

1) Subarachnoid bleeds
2) Subdural bleeds

Answer 3

1) Arterial - develop quickly

2) Venous - develop slowly

Question 4

Which brain arteries are most at risk of rupturing in chronic hypertension?

Answer 4

Short perforating arteries (which supply the basal ganglia and thalamus)

Question 5

What is small vessel disease

Answer 5

Chronic hypertension causing occlusions/lesions of long perforating arteries which supply the white matter of neurones in the brain

IMG 180

Question 6

What is the border between territories of two main cerebral arteries known as?

What is the clinical significance of these regions?

Answer 6

Watershed regions

These are sensitive to drops in arterial pressure and more vulnerable to emboli because they are most distal to each supplying artery

Question 7

What is the definition of the following with regard to cerebrovascular anatomy;

1) Anterior circulation?
2) Posterior circulation?

What is supplied by each?

Answer 7

1) Blood supply via the internal carotid arteries
• Frontal lobe
• Parietal lobes
• Striatum and globus pallidus

2) Blood supply via vertebral arteries
• Thalamus
• Occipital lobe (basomedially)
• Temporal lobes (basomedially)

IMG 179

Question 8

What are lacunar infarcts often a consequence of?

Answer 8

Small vessel disease from chronic hypertension

Question 9

What is the most common genetic cause of vascular dementia and lacunar infarcts? What gene causes it?

Answer 9

Cerebral Autosomal Dominant Arteriopathy with Subcortical Infarcts and Leukoencephalopathy (CADASIL)
• Mutation in NOTCH3 gene
• Chromosome 19

Question 10

Which of the following is technically referred to as a stroke?
• Epidural haemorrhage
• Subdural haemorrhage
• Subarachnoid haemorrhage

Answer 10

Subarachnoid - in direct contact with brain tissues

Question 11

What are the types of cerebral oedema?

Answer 11

Vasogenic oedema:
• Rupture of BBB causing increased extracellular fluid

Cytotoxic oedema:
• Cell injury in the brain releasing the intracellular fluid

NB: conditions associated with more generalised oedema will have elements of both (e.g. stroke), whereas more local oedema will be a result of one or another

Question 12

Describe the morphological changes seen in cerebral oedema?

What are the possible consequences?

Answer 12

• Softer brain
  
  • Gyri are flat and Sulci are narrow
  • Ventricles compressed

Consequences:
• Papilledema (swelling of optic disc)
• Third cranial nerve palsy
• Brain herniations

Question 13

What are the signs of an oculomotor III palsy (resulting from raised intracranial pressure?

Answer 13

• Ptosis (levator palpebrae?)
  
  • Lateral deviation of eye (LR6)
  • Dilation of the pupil

Question 14

What are the possible directions of brain herniation in episodes of increased intracranial pressure?

Describe what happens in each?

Which compresses the ACA and which compresses the PCA?

Answer 14

Subfalcine cingulate gyrus herniation
• Asymmetric expansion of the cerebral hemispheres displaces the cingulate gyrus underneath the falx cerebri
• Compresses ACA

Transtentorial herniation
• Medial aspect of the temporal lobe is compressed against the free margin of the tentorium cerebelli
• Oculomotor nerve and PCA become compressed